1. Field of the Invention
The invention relates to a method for converting an input image sequence composed of line-interlaced half-frames at a first repetition frequency to an output image sequence composed of progressive images at a second repetition frequency, which is twice the first. The invention also relates to a circuit configuration for such a conversion.
In order to produce a television picture which is as free of flicker as possible, previous solution approaches are based on the conversion of the signal which is transmitted at the transmitter end and contains line-interlaced fields at a field repetition frequency of 50 or 60 Hz to a field sequence at a field repetition frequency of 100 or 120 Hz, respectively. Such a conversion is described, for example, in European published patent application EP 0 727 904 A2. Other methods provide for the conversion to an image sequence composed of progressive images at a frame refresh rate of 50 or 60 Hz, in which case the progressive images contain the entire number of lines. That method is described, for example, in European published patent application EP 0 679 022 A2.
Flicker effects are still perceptible both with field sequences at 100/120 Hz and with progressive image sequences at 50/60 Hz. In the former case, the edge flickering is admittedly reduced, but it is not completely corrected. Furthermore, line wandering may still occur. In the latter method, the large-area flickering is not completely surpressed.